The long-term goal of the proposed research is to develop an improved capability for immunodiagnosis of ocular toxocariasis. Ocular toxocariasis is a zoonosis, frequently affecting children, which may result in considerable ocular disease. It is important to accurately diagnose ocular toxocariasis when the disease presentation and medical history are typical of infection with larval Toxocara canis. Furthermore, ocular toxocariasis is a disease condition which is often considered in the differential diagnosis of other serious diseases, such as retinoblastoma. Accordingly, it is important to reliably exclude ocular toxocariasis from certain differential diagnoses. Specific goals of the proposed research include the development of improved antibody-detection assays using larval excretory-secretory antigen fractions which have been purified by physicochemical and immunochemical means. Assays will also be developed for the detection and measurement of soluble parasite antigens. Methods will be developed initially using biological fluids, ie. serum, ocular fluids and cerebrospinal fluid, obtained from experimentally infected laboratory animals. As methods are perfected, they will be adapted for use in humans using available material. Finally, in order to develop a capability for retrospective diagnosis of ocular toxocariasis, methods will be developed for detection of parasite antigen in pathologic specimens.